<p align="center">
  <a href="http://srtalliance.org/">
    <img alt="SRT" src="http://www.srtalliance.org/wp-content/uploads/SRT_text_hor_logo_grey.png" width="600"/>
  </a>
</p>

[![Build Status Linux and macOS][travis-badge]][travis]
[![Build Status Windows][appveyor-badge]][appveyor]
[![License: MPLv2.0][license-badge]](./LICENSE)
[![Latest release][release-badge]][github releases]
[![Debian Badge][debian-badge]][debian-package]

# Introduction

Secure Reliable Transport (SRT) is an open source transport technology that optimizes streaming performance across unpredictable networks, such as the Internet.

|    |    |
| --- | --- |
| **S**ecure | Encrypts video streams |
| **R**eliable | Recovers from severe packet loss |
| **T**ransport | Dynamically adapts to changing network conditions |

SRT is applied to contribution and distribution endpoints as part of a video stream workflow to deliver the best quality and lowest latency video at all times.

As audio/video packets are streamed from a source to a destination device, SRT detects and adapts to the real-time network conditions between the two endpoints. SRT helps compensate for jitter and bandwidth fluctuations due to congestion over noisy networks, such as the Internet. Its error recovery mechanism minimizes the packet loss typical of Internet connections. And SRT supports AES encryption for end-to-end security, keeping your streams safe from prying eyes.

[Join the conversation](https://slackin-srtalliance.azurewebsites.net/) in the `#development` channel on [Slack](https://srtalliance.slack.com).

# Guides
* [Why SRT Was Created](docs/why-srt-was-created.md)
* [SRT Protocol Technical Overview](https://github.com/Haivision/srt/files/2489142/SRT_Protocol_TechnicalOverview_DRAFT_2018-10-17.pdf)
* SRT Cookbook: [website](https://srtlab.github.io/srt-cookbook/protocol/threads/), [GitHub](https://github.com/SRTLab/srt-cookbook)
* SRT RFC: [txt](https://haivision.github.io/srt-rfc/draft-sharabayko-mops-srt.txt), [html](https://haivision.github.io/srt-rfc/draft-sharabayko-mops-srt.html), [GitHub](https://github.com/Haivision/srt-rfc)
* [Using the `srt-live-transmit` App](docs/srt-live-transmit.md)
* [Contributing](docs/Contributing.md)
* [Developer's Guide](docs/DevelopersGuide.md)
* [SRT Encryption](docs/encryption.md)
* [API](docs/API.md)
* [Reporting problems](docs/reporting.md)

# Requirements

* cmake (as build system)
* Tcl 8.5 (optional for user-friendly build system)
* OpenSSL
* Pthreads (for POSIX systems it's builtin, for Windows there's a library)

For detailed description of the build system and options, please read [BuildOptions.md](docs/BuildOptions.md).

## For Linux:

Install cmake and openssl-devel (or similar name) package. For pthreads
there should be -lpthreads linker flag added.

Default installation path prefix of `make install` is `/usr/local`.

To define a different installation path prefix, use the `--prefix` option with `configure`
or [`-DCMAKE_INSTALL_PREFIX`](https://cmake.org/cmake/help/v3.0/variable/CMAKE_INSTALL_PREFIX.html) CMake option.

To uninstall, call `make -n install` to list all the dependencies, and then pass the list to `rm`.

### Ubuntu 14
```
sudo apt-get update
sudo apt-get upgrade
sudo apt-get install tclsh pkg-config cmake libssl-dev build-essential
./configure
make
```
### CentOS 7
```
sudo yum update
sudo yum install tcl pkgconfig openssl-devel cmake gcc gcc-c++ make automake
./configure
make
```
### CentOS 6
```
sudo yum update
sudo yum install tcl pkgconfig openssl-devel cmake gcc gcc-c++ make automake
sudo yum install centos-release-scl-rh devtoolset-3-gcc devtoolset-3-gcc-c++
scl enable devtoolset-3 bash
./configure --use-static-libstdc++ --with-compiler-prefix=/opt/rh/devtoolset-3/root/usr/bin/
make
```


## For Mac (Darwin, iOS):

[Homebrew](https://brew.sh/) supports "srt" formula.

```shell
brew update
brew install srt
```

If you prefer using a head commit of `master` branch, you should add `--HEAD` option
to `brew` command.

```shell
brew install --HEAD srt
```

Also, SRT can be built with `cmake` and `make` on Mac.
Install cmake and openssl with development files from "brew". Note that the
system version of OpenSSL is inappropriate, although you should be able to
use any newer version compiled from sources, if you prefer.

```shell
brew install cmake
brew install openssl
export OPENSSL_ROOT_DIR=$(brew --prefix openssl)
export OPENSSL_LIB_DIR=$(brew --prefix openssl)"/lib"
export OPENSSL_INCLUDE_DIR=$(brew --prefix openssl)"/include"
./configure
make
```

## For Windows:

Follow the [Windows build instructions](docs/build-win.md).

[appveyor-badge]: https://img.shields.io/appveyor/ci/Haivision/srt/master.svg?label=Windows
[appveyor]: https://ci.appveyor.com/project/Haivision/srt
[travis-badge]: https://img.shields.io/travis/Haivision/srt/master.svg?label=Linux/macOS
[travis]: https://travis-ci.org/Haivision/srt
[license-badge]: https://img.shields.io/badge/License-MPLv2.0-blue

[github releases]: https://github.com/Haivision/srt/releases
[release-badge]: https://img.shields.io/github/release/Haivision/srt.svg

[debian-badge]: https://badges.debian.net/badges/debian/testing/libsrt1/version.svg
[debian-package]: https://packages.debian.org/testing/libsrt1